Various materials, both hazardous and nonhazardous, are stored in compressed gas and liquefied cylinders. Such materials may be liquid, gaseous or solid in form. The containment and transfer of hazardous material is of concern. Chlorine gas is but one example of a hazardous material. Exposure to chlorine gas can result in severe lung irritation and death. Cylinders containing chlorine and other hazardous materials are therefore clearly marked and preferably kept in the best possible condition. Each year, however, numerous compressed gas and liquefied cylinders in damaged, deteriorated or unmarked condition are discovered at industrial plants, research facilities, and hazardous waste sites. These cylinders contain unknown, oftentimes dangerous, materials. To facilitate sampling and identification of unknown gases, liquids and solids, and to allow safe recontainerization and disposal of these dangerous materials, the cylinder must be depressurized, the contained material removed from the cylinder for evaluation and then transferred to intact, stable containers. Once the material is identified and contained in an intact, marked cylinder, the material can be shipped for disposal or otherwise. Some cylinders may contain material that exists in a liquid phase and upon depressurization of the cylinder, may not volatize into a gaseous state. Therefore, transfer of liquid material from the original cylinder to the intact container may be required. In fact, transfer of the original cylinder contents to the intact cylinders typically involves transferring both gases and liquids, and oftentimes the transfer of solid matter.
Great care must be taken when depressurizing a cylinder to prevent potentially hazardous gases and liquids from escaping to the environment. In addition, releasing the compressed gas must be carefully conducted to prevent the cylinder from sudden, missle-like propulsion. Such problems have been addressed in U.S. Pat. Nos. 4,690,180 (hereinafter the "'180 patent") and 4,944,333 (hereinafter the "'333 patent").
The '180 and '333 patents disclose techniques for the removal and disposal of contents from compressed gas cylinders whereby the cylinder is punctured at and along its mid-section. The cylinder is first horizontally positioned on V-shaped supports within an evacuated enclosure. Inert gases are introduced into the enclosure and the cylinder is both restrained and punctured by a punch-press type or drill assembly. This results in a hole or holes being formed along the mid-section of the cylinder to provide a path through which gases and liquids may drain from the cylinder into the enclosure. Hydraulic actuators are provided on the enclosure to allow manipulation or rocking of the enclosure to aid in drainage of the contents from the cylinder. The drained fluids and gases are then forced (by pressurization of the enclosure) or pumped from the enclosure for sampling and transfer to intact cylinders for shipping.
While suitable in many respects, these techniques have certain inherent disadvantages. One disadvantage is that puncturing the cylinder poses a sparking or explosion hazard when practiced on cylinders containing unstable, flammable gases. The action of the punch-press type assembly can cause a spark and a resulting explosion. An explosion may not only compromise the integrity of the enclosure but can cause damage to the internal mechanical parts. Of course, an explosion of sufficient strength could injure an operator. Another disadvantage is that no provision is made to decontaminate the interior of the enclosure or the interior of the cylinder. Once the gases have been discharged, the cylinder may remain contaminated by residual waste in the form of liquids or radioactive particles or otherwise. Incomplete decontamination of the cylinder can lead to a release of hazardous waste into the environment. Another disadvantage is that the cylinder is usually secured along only one axis. As such, the cylinder is susceptible to sudden release or propulsion upon decompression of the cylinder. Even when only a small hole is made in the side of the cylinder, the rapid escape of the compressed gas can cause the cylinder to spin or otherwise move. Yet another disadvantage of the devices shown in the '180 and '333 patents is that drainage of the fluid in cylinder may be inefficient or incomplete because the cylinder is positioned substantially horizontally and dependent upon rocking of the enclosure for drainage. It should be noted that rocking of the enclosure requires repetitive manipulation thereof. Even so, it is practically impossible to drain the cylinder completely since fluid can only exit the cylinder through a small hole at the location of the puncture.
It should be further noted that the art has yet to provide any back-up system whereby the cylinder may be emptied even though the primary system has failed. For example, should the puncturing mechanism prove ineffective or partially ineffective for any reason, no secondary system has been provided whereby decompressurization can be effected or completed. It is dangerous to open the enclosure and handle the cylinder when the decompressurization operation is only partially complete. Further, it is difficult to perform maintenance on the internal components when they are contaminated since persons performing such maintenance must wear protective clothing that decreases maneuverability and dexterity.
Thus, there is a need in the art for an improved method and apparatus for removing the contents of compressed gas and liquid cylinders.